A technology for allocating plural functions to a key is known (for example, refer to Japanese Patent Publication No. 09-120352 to Seki et al.). Such a technology is used for an information processing device such as a mobile phone, which has fewer keys than the number of functions to be implemented using the keys. Such a key is referred to as a “soft key” or “software key” because a function allocated to the key is determined depending on software in use.
To allocate plural functions to a key, a function currently allocated to the key is displayed, as disclosed in Japanese Patent Publication No. 09-120352 to Seki et al. According to this technology, a user can recognize a function currently allocated to the key.